Phanerozoic orogeny triggers reactivation and exhumation in the northern part of the Archean–Paleoproterozoic North China Craton

• Hongqiyingzi Group underwent episodic tectonothermal events from Archean to Phanerozoic.
• TNCO Paleoproterozoic subduction at 1.95 Ga and collision at 1.85 Ga.
• 460–420 Ma concordant zircons record the onset of TNCO exhumation.
• Ubiquitous 360–320 Ma concordant zircons reveal major period exhumation.
• Young orogeny heavily triggered Archean crust and Paleoproterozoic orogen reactivation.

Cratons and orogenic belts are integral components of ancient continents. In some cases, stable continents can be reactivated and even largely destroyed by younger events. The mechanisms of reactivation or destruction of ancient cratons remain equivocal. Here we compile zircon U–Pb data from the metamorphic rocks of the Hongqiyingzi Group in the northern part of the North China Craton (NCC) to evaluate this problem. The results reveal episodic tectonothermal events related to three major periods of Latest Neoarchean–Earliest Paleoproterozoic (2.6–2.4 Ga), Paleoproterozoic (1.85–1.95 Ma) and Phanerozoic (480–220 Ma, with peak at 360–320 Ma). The Neoarchean–Paleoproterozoic crust as represented by the Hongqiyingzi Group was subducted to eclogite facies at ca. 1.95 Ga, followed by the final collision between the Eastern and Western Blocks at ca. 1.85 Ga to produce the Trans-North China Orogen (TNCO). The ubiquitous presence of Phanerozoic concordant zircons in the Hongqiyingzi Group suggests the episodic exhumation of the TNCO in the northern segment during the Phanerozoic. The 460–420 Ma concordant zircons record the onset of exhumation, triggered by the Ordovician–Silurian southward subduction of the Paleoasian Ocean. Widespread occurrence of 360–320 Ma metamorphic and magmatic zircons in the Hongqiyingzi Group demonstrates that the Carboniferous–Permian was an important period of exhumation for the TNCO, possibly related to back-arc extension. A few Permian–Triassic concordant zircons record late Permian accretion and Triassic post-accretional uplifting. Our study demonstrates that the young orogeny during the formation of the Central Asian Orogenic Belt resulted in extensive reactivation of not only the Archean continental crust but also the Paleoproterozoic orogen in the northern NCC.

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